This invention relates to methods of using inhibitors of the CD2/LFA-3 interaction in treating skin conditions characterized by increased T cell activation and abnormal antigen presentation in the dermis and epidermis in mammals, including humans. Such conditions include psoriasis, UV damage, e.g., photoaging, atopic dermatitis, cutaneous T cell lymphoma such as mycosis fungoides, allergic and irritant contact dermatitis, lichen planus, alopecia areata, pyoderma gangrenosum, vitiligo, ocular cicatricial pemphigoid, and urticaria.
There are numerous skin conditions characterized by increased T cell activation and abnormal antigen presentation in the dermis and epidermis. The pathophysiologic mechanisms involved in the evolution of such inflammatory processes are poorly understood. However, it has become apparent that skin cells are important in the generation of a cutaneous inflammatory response (Kupper, xe2x80x9cImmune and Inflammatory Processes in Cutaneous Tissuesxe2x80x9d, J. Clin. Invest., 86, pp. 1783-89 (1990)).
The normal adult epidermal population contains 1-2% Langerhans"" cells and about 98% keratinocytes. Keratinocytes and other nonhematopoietically-derived cells resident in skin contribute to immune homeostasis and can produce various cytokines which influence migration of T cells and expression of adhesion molecules.
As antigen presenting cells, Langerhans"" cells express a high density of Class II major histocompatibility complex (MHC) antigen on the cell surface. MHC Class II molecules bind peptides derived from endocytosed antigen and are recognized primarily by helper T lymphocytes. The T cell receptor on T cells recognizes antigen as a peptide fragment bound to the cell-surface molecules encoded by the MHC (Springer, xe2x80x9cAdhesion Receptors of the Immune Systemxe2x80x9d, Nature, 346, pp. 425-27 (1990)).
There are many interactions between molecules expressed on the surface of Langerhans"" cells and the surface of T cells, in addition to the T cell receptor/MHC interaction. These surface molecules, often referred to as adhesion molecules, participate in a number of functions including cellular adhesion, antigen recognition, co-stimulatory signalling in T cell activation and stimulation of effectors of T cell cytotoxicity (xe2x80x9cAdhesion Molecules in Diagnosis and Treatment of Inflammatory Diseasesxe2x80x9d, The Lancet, 336, pp. 1351-52 (1990)). Such cell adhesion appears to be involved in activation of T cell proliferation in the generation of an immune response (Hughes et al., xe2x80x9cThe Endothelial Cell as a Regulator of T-cell Functionxe2x80x9d, Immunol. Rev., 117, pp. 85-102 (1990)).
Various skin conditions are characterized by increased T cell activation and abnormal antigen presentation in the dermis and epidermis (Cooper, xe2x80x9cImmunoregulation in the Skinxe2x80x9d, in Cutaneous Lymphoma, Curr. Probl. Dermatol., eds. van Vloten et al., 19, pp. 69-80 at pp. 73, 74, 76 (1990)). For example, in contact allergic dermatitis, activation of intracutaneous T cells is observed. It is known that skin from patients exhibiting atopic dermatitis contains an increased number of Langerhans"" cells (Cooper, xe2x80x9cImmunoregulation in the Skinxe2x80x9d, in Cutaneous Lymphoma, Curr. Probl. Dermatol., eds. van Vloten et al., 19, at p. 74 (1990)). In psoriatic skin, there is an increased number of antigen presenting cells, composed of both Langerhans"" cells and non-Langerhans"" cell Class II MHC-bearing antigen presenting cells (Cooper, xe2x80x9cImmunoregulation in the Skinxe2x80x9d, in Cutaneous Lymphoma, Curr. Probl. Dermatol., eds. van Vloten et al., 19, at p. 75 (1990)).
UV exposed skin is characterized by an overall depletion of Langerhans"" cells and migration of a non-Langerhans"" cell antigen-presenting cell population into the epidermis, which activates autologous T cells to proliferate (Cooper, xe2x80x9cImmunoregulation in the Skinxe2x80x9d in Cutaneous Lymphoma, Curr. Probl. Dermatol., eds. van Vloten et al., 19, at pp. 75-76 (1990)). In human skin after 4 minimal erythemal doses of UV B, Langerhans"" cells (the constitutive antigen presenting cell population) are inactivated for approximately 3 days (Cooper et al., xe2x80x9cEffects Of Ultraviolet Radiation On Human Epidermal Cell Alloantigen Presentation: Initial Depression Of Langerhans Cell-Dependent Function Is Followed By Appearance Of T6-DR+ Cells That Enhance Epidermal Alloantigen Presentationxe2x80x9d, J. Immunol., 134, pp. 129-37 (1985)). In this type of UV damaged skin, the CD1axe2x88x92DR+ macrophage population (a population of antigen presenting cells) increases from 0% (normal skin) to approximately 2-10% of the entire epidermal cell population and is the cell population entirely responsible for the induction of T cell proliferation to alloantigen. (Cooper et al., J. Immunol., supra (1985); Baadsgaard et al., xe2x80x9cIn Vivo Ultraviolet-Exposed Human Epidermal Cells Activate T Suppressor Cell Pathways That Involve CD4+ CD45RA+ Suppressor-Inducer T Cellsxe2x80x9d, J. Immunol., 145, pp. 2854-61 (1990)).
Cutaneous T cell lymphoma is characterized by the expansion of a malignant clonal population of T cells in the dermis and epidermis. Lesional epidermal cells contain increased numbers of CD1+DR+ antigen presenting cells (Cooper, xe2x80x9cImmunoregulation in the Skinxe2x80x9d in Cutaneous Lymphoma, Curr. Probl. Dermatol., eds. van Vloten et al., 19, at pp. 76-77 (1990)).
Presently known therapies for the above mentioned skin diseases are inadequate. Steroids or cyclosporin A are commonly used in the treatment of psoriasis, lichen planus, urticaria, atopic dermatitis, UV damage, pyoderma gangrenosum, vitiligo, ocular cicatricial pemphigoid, alopecia areata, allergic and irritant contact dermatitis and cutaneous T cell lymphoma. In addition, for some of these skin conditions, various therapies include retinoids, PUVA, nitrogen mustard, interferon, chemotherapy, methotrexate, UV light, antibiotics and antihistamines. See generally Fitzpatrick, Dermatology in General Medicine, 3rd ed., McGraw Hill (1987).
Side effects to these therapies are known. Most commonly encountered drawbacks for cyclosporin A include toxicity due to immunosuppression and renal and neural toxicity. Steroids have well known side effects including induction of Cushing Syndrome. Side effects of certain of the other aforementioned therapies include skin cancer, bone marrow and constitutional toxicities, ligament calcification, liver fibrosis and other disorders.
T cells play a major role in the immune response by interacting with target and antigen presenting cells. For example, T cell-mediated killing of target cells is a multi-step process involving, initially, adhesion of cytolytic T cells (the effector cells) to target cells. Also, helper T cells help initiate the immune response by adhesion to antigen presenting cells.
These interactions of T cells with target and antigen presenting cells are highly specific and depend on the recognition of an antigen on the surface of a target or antigen presenting cell by one of the many specific antigen receptors on the surface of T cells.
The receptor-antigen interaction of T cells and other cells is also facilitated by various T cell surface proteins, e.g., the antigen-receptor complex CD3 and accessory adhesion molecules such as CD4, LFA-1, CD8, and CD2. It is also facilitated by accessory adhesion molecules, such as LFA-3, ICAM-1 and MHC, that are expressed on the surface of the target or antigen presenting cells. For example, LFA-1 and its counter receptor ICAM-1 or ICAM-2, as well as CD2 and its counter receptor LFA-3 have been implicated in cellular adhesion and T cell activation. It is known that the LFA-1/ICAM and CD2/LFA-3 interactions are independent.
A number of other molecules present on resting T cells have also been implicated in T cell adhesion, including E2 (MIC2), VLA-4 (CD49d), CD44 (Hermes, Pgp-1, ECMRIII), and H19 (N4) (see Makgoba et al., xe2x80x9cThe CD2-LFA-3 and LFA-1-ICAM Pathways: Relevance to T-cell Recognitionxe2x80x9d, Immunol. Today, 10, pp. 417-22 (1989)).
One way in which T cells are activated is by binding of their antigen specific T cell receptors to peptide-MHC complexes on the surface of antigen presenting cells such as macrophages. T cell activation stimulates proliferation and differentiation of two types of functional T cells: helper cells, which promote the proliferation and maturation of antibody-producing B lymphocytes, and killer cells, which lyse target cells (Bierer et al., xe2x80x9cA Monoclonal Antibody to LFA-3, the CD2 Ligand, Specifically Immobilizes Major Histocompatibility Complex Proteinsxe2x80x9d, Eur. J. Immunol., 19, pp. 661-65 (1989); Springer xe2x80x9cAdhesion Receptors of the Immune Systemxe2x80x9d, Nature, 346, pp. 425-34 (1990)).
The interaction between CD2 and LFA-3 remains poorly understood with respect to activation of T cell activity. Recent studies have suggested that there is a specific interaction between CD2 (a T cell adhesion molecule) and LFA-3 (a target cell and antigen presenting cell adhesion molecule) which mediates T cell adhesion to the target or antigen presenting cells. This cell-cell adhesion has been implicated in the initiation of T cell functional responses (Dustin et al., xe2x80x9cPurified Lymphocyte Function Associated Antigen 3 Binds to CD2 and Mediates T Lymphocyte Adhesion,xe2x80x9d J. Exp. Med., 165, pp. 677-92 (1987); Springer et al., xe2x80x9cThe Lymphocyte Function-associated LFA-1, CD2, and LFA-3 Molecules: Cell Adhesion Receptors of the Immune Systemxe2x80x9d, Ann. Rev. Immunol., 5, pp. 223-52 (1987)).
LFA-3, which is found on the surface of a wide variety of cells, including human erythrocytes, has become the subject of a considerable amount of study to further elucidate its role in various T cell interactions (see, e.g., Krensky et al., xe2x80x9cThe Functional Significance, Distribution, and Structure of LFA-1, LFA-2, and LFA-3: Cell Surface Antigen Associated with CTL-Target Interactionsxe2x80x9d, J. Immunol., 131(2), pp. 611-16 (1983); Shaw et al., xe2x80x9cTwo Antigen-Independent Adhesion Pathways Used by Human Cytotoxic T-cell Clonesxe2x80x9d, Nature, 323, pp. 262-64 (1986)). Two natural forms of LFA-3 have been identified. One form of LFA-3 (xe2x80x9ctransmembrane LFA-3xe2x80x9d) is anchored in the cell membrane by a transmembrane hydrophobic domain. cDNA encoding this form of LFA-3 has been cloned and sequenced (see, e.g., Wallner et al., xe2x80x9cPrimary Structure of Lymphocyte Function-Associated Antigen-3 (LFA-3)xe2x80x9d, J. Exp. Med., 166, pp. 923-32 (1987)). Another form of LFA-3 is anchored to the cell membrane via a covalent linkage to phosphatidylinositol (xe2x80x9cPIxe2x80x9d)-containing glycolipid. This latter form has been designated xe2x80x9cPI-linked LFA-3xe2x80x9d, and cDNA encoding this form of LFA-3 has also been cloned and sequenced (Wallner et al., PCT Publn. WO 90/02181).
The human CD2 (T11) molecule is a 50 kD surface glycoprotein expressed on  greater than 95% of thymocytes and virtually all peripheral T lymphocytes. Biochemical analyses using specific monoclonal antibodies have suggested that CD2 is T lineage-specific and exists on the cell surface in several differentially glycosylated forms (Howard et al., xe2x80x9cA Human T Lymphocyte Differentiation Marker Defined by Monoclonal Antibodies that Block E-Rosette Formationxe2x80x9d, J. Immunol., 126, pp. 2117-22 (1981); Brown et al., in Leukocyte Typing III, ed. McMichael, Oxford University Press, pp. 110-12 (1987); Sayre et al., xe2x80x9cMolecular Cloning and Expression of T11 cDNAs Reveals a Receptor-Like Structure on Human T Lymphocytesxe2x80x9d, Proc. Natl. Acad. Sci. USA, 84, pp. 2941-45 (1987)).
The sequence of a human CD2 gene has been reported (Seed and Aruffo, xe2x80x9cMolecular Cloning of the CD2 Antigen, the T-cell Erythrocyte Receptor, by a Rapid Immunoselection Procedurexe2x80x9d, Proc. Natl. Acad. Sci. USA, 84, pp. 3365-69 (1987); Sayre et al., xe2x80x9cMolecular Cloning and Expression of T11 cDNAs Reveal a Receptor-like Structure on Human T Lymphocytesxe2x80x9d, Proc. Natl. Acad. Sci. USA, 84, pp. 2941-45 (1987)). CD2 cDNA clones predict a cleaved signal peptide of 24 amino acid residues, an extracellular segment of f 185 residues, a transmembrane domain of 25 residues and a cytoplasmic region of 117 residues (Sayre et al., supra (1987); Sewell et al., xe2x80x9cMolecular Cloning of the Human T-Lymphocyte Surface CD2 (T11) Antigenxe2x80x9d, Proc. Natl. Acad. Sci. USA, 83, pp. 8718-22 (1986); Seed and Aruffo, supra (1987); Clayton et al., Eur. J. Immunol., 17, pp. 1367-70 (1987)).
Soluble CD2 polypeptides having an LFA-3 binding domain have been reported (PCT Publn. WO 90/08187).
Monoclonal antibodies to CD2, for example TS2/18, T111, T112, T113, and to LFA-3, for example TS2/9, have also been reported (see, e.g., Hughes et al., xe2x80x9cThe Endothelial Cell as a Regulator of T-Cell Functionxe2x80x9d, Immunol. Reviews, 117, pp. 85-102 (1990); Meuer, xe2x80x9cAn Alternative Pathway of T-Cell Activation: A Functional Role for the 50 kD T11 Sheep Erythrocyte Receptor Proteinxe2x80x9d, Cell, 36, pp. 897-906 (1984)).
The need still exists for improved methods of preventing and treating skin conditions exhibiting increased T cell activation and abnormal antigen presentation.
The present invention generally solves many of the problems referred to above. It for the first time provides a method of preventing or treating skin conditions, characterized by increased T cell activation and abnormal antigen presentation in the dermis and epidermis, in a mammal, whereby an inhibitor of the CD2/LFA-3 interaction, is administered to the mammal. The methods of this invention are superior to previously available therapies for these skin conditions for many reasons, including less immunosuppression than pre-existing therapies and more specific therapy with less general toxicity.
The method of the present invention preferably will be used in the treatment or prophylaxis of skin conditions selected from psoriasis, UV damage, e.g., photoaging, atopic dermatitis, cutaneous T cell lymphoma such as mycosis fungoides, allergic and irritant contact dermatitis, lichen planus, alopecia areata, pyoderma gangrenosum, vitiligo, ocular cicatricial pemphigoid, and urticaria, preferably psoriasis or UV damage.
Inhibitors that can be used in accordance with the method of the present invention include any molecule that inhibits the CD2/LFA-3 interaction. Preferably, the inhibitor is selected from the group consisting of anti-LFA-3 antibody homologs, anti-CD2 antibody homologs, soluble LFA-3 polypeptides, small molecules, e.g., carbohydrates, soluble CD2 polypeptides, CD2 or LFA-3 mimetic agents and derivatives thereof.